This invention relates to pneumatic control systems. In particular, it relates to pneumatic control systems used for starting a system for thermal conditioning of air in an enclosed space.
Many buildings such as office buildings, stores and factories are occupied or used only during predetermined hours and days of the week. Accordingly, in order to save energy and expenditures, the system for thermal conditioning of air inside the buildings (i.e. a cooling or a heating system) is rendered inoperative during the hours when the building is not occupied or used. The heating or the cooling system must however be restarted prior to the scheduled arrival of the occupants or users of the building, so that the temperature of the air inside the building is at a comfortable level by the time the users or occupants arrive. Since the amount of time needed to reach a comfortable temperature inside the building depends upon the temperature inside at the time the heating or cooling system is restarted, the re-start system is inefficient where the temperature differential between the desired temperature and the initial temperature is small. For example, the heating system might be programmed to be started at 6:00 A.M. during the winter in order to bring the temperature inside the enclosed space to a comfortable level by 9:00 A.M. When the temperature differential between the initial level and the comfortable level is small, the temperature inside the enclosed space will reach the desired level prior to 9:00 A.M. On the other hand, if the temperature differential is higher than expected, then the temperature of the enclosed space is still uncomfortable at the time the occupants or users of the building arrive. Similar problems arise when cooling of air in the enclosed space is required. Considerable energy savings may be realized if the heating or cooling system is started at the optimum time, thus enabling the enclosed space to reach a desired comfort level at time of occupancy. Accordingly, there is a need for a control system which delays or accelerates the restarting of the thermal conditioning system depending on the initial temperature of the enclosed space.
Several approaches have been proposed for developing a system that controls the restart time of the conditioning system. For example. U.S. Pat. Nos. 4,106,690; 3,317,692; 3,974,059; 4,040,565; 2,569,530; and 3,964,674 disclose such systems. The present invention provides an improved system for accomplishing the above-mentioned task.
The improved system of the present invention is a pneumatic system which is simple and inexpensive to construct and to maintain. The pneumatic control system of the present invention is also particularly suited for inclusion in already installed systems which are entirely pneumatic.
Thus, one object of the present invention is to provide a pneumatic system for controlling the starting time of the cooling or heating system depending on the initial sensed temperature.
Another object of the present invention is to provide a pneumatic system for controlling the starting time of a thermal conditioning system, which is relatively inexpensive, and simple and inexpensive to install and maintain.
Other objects of the present invention will become apparent to those skilled in the art upon studying this disclosure.